1. Field of the Invention
This invention relates to a telescopic boom structure and more particularly to a vehicle mounted telescopic boom structure. Even more particularly, this invention relates to a vehicle mounted telescopic boom structure which includes a swing-under extension boom which is pivotally secured to the outer end of a jib boom which is pivotally secured to the outer end of the boom structure. A personnel basket is secured to the outer end of the extension boom. The personnel basket remains attached to the extension boom and is stowed on the deck of the vehicle when the boom structure, jib boom and extension boom are in their stowed positions.
2. Description of the Related Art
In the construction or maintenance of tall power or transmission lines, access to the work thereon is accomplished with a long boom, boom trucks (cranes) with swing around extensions (jibs) and manned basket attachments. The problem with the prior art truck mounted telescopic boom structures is that the personnel basket which is secured to the outer end of the jib boom must be disconnected from the jib boom when the boom structure and jib boom are in their stowed positions so that the personnel basket may be stowed on the deck of the truck.
In the prior art boom structures, when it is desired to operate the boom structure, the personnel basket, which had previously disconnected from the jib boom, must be lifted from the deck and moved many feet away from the truck and placed on the ground. The boom structure is then raised and pivoted from its stowed position with respect to the truck with the jib boom then being pivotally moved to its extended or operative position. The boom structure, jib boom and personnel basket must be manipulated so as to permit the personnel basket to be attached to the outer end of the jib boom. When the job has been finished, or the truck is going to be moved to another power pole, the personnel basket is placed on the ground and the jib boom is disconnected therefrom. The jib boom and boom structure are then moved to their stowed positions and the personnel basket is then moved to the deck of the truck. The requirement that the personnel basket be connected to the jib boom and disconnected from the jib boom as described above involves extensive time and manpower.
U.S. Pat. No. 9,926,670 which is owned by the assignee of the instant invention, describes a stowable jib boom with a stowable personnel basket. Although the invention of the '670 Patent does permit the personnel basket to be stowed on the deck of the truck without disconnecting the personnel basket from the jib boom, the personnel basket must be designed so as to be fairly narrow so as to not exceed the highway over-width restrictions since the basket is stowed at one side of the boom structure and jib boom.